1. Field of the Invention
The present invention relates to a surface mountable electronic part wherein a circuit substrate is covered with a shield case like a hybrid IC, for example.
2. Prior Art
Conventionally, a surface mountable electronic part of this kind shown in FIG. 6 and FIG. 7 is known. A circuit substrate 31 is provided in the surface mountable electronic part 30. F-shaped terminals 32 for an external connection are connected and fixed to end parts of the circuit substrate 31. The circuit substrate 31 is covered with a metal case 34 having a ground terminal 33 and shielded.
The surface mountable electronic part 30 is subjected to a surface mounting on a substrate for mounting (not shown in the drawings) by the F-shaped terminals 32 and the ground terminal 33.
The above mentioned conventional surface mountable electronic part 30 has the following problems:
(1) Since a fitting of the F-shaped terminals 32 and a fitting of the metal case 34 need to be conducted separately, a rationalization of the process is prevented.
(2) It is difficult to construct and fit the F-shaped terminals 32 and the metal case 34 precisely due to the structure, and a longitudinal fitting size shown as L1 and L2 in the drawing and a lateral fitting size shown as D1 and D2 in the drawing cannot be secured accurately. When a precision of the longitudinal fitting size is not accurate, not only is the surface mountable electronic part 30 unstable (a mounting on the substrate for mounting is unstable), but also a solderability is reduced. Further, when a precision of the lateral fitting size is not accurate, the F-shaped terminals 32 and the ground terminal 33 do not fit a soldering land of the substrate for mounting accurately and a connection becomes incomplete.
(3) In this structure, regular space needs to be provided between the metal case 34 and the F-shaped terminals 32 (D1 and D2 correspond to the space) in order to prevent a short circuit. However, as mentioned above, since it is difficult to secure the size with precision, it is necessary to form the space D1 and D2 with plenty of room. Therefore, more space than needed is provided between the metal case 34 and the circuit substrate 31 and a shield becomes incomplete.
(4) Since the F-shaped terminals 32 are electrically connected to the circuit substrate 31 and besides, it is necessary to secure the fitting strength, the size of the soldering land shown in the drawing as D3 must be made sufficiently large. Therefore, the area occupied by a connection of the F-shaped terminals 32 on the surface of the circuit substrate 31 becomes large and as a result, the surface mountable electronic part 30 is prevented from being miniaturized.